The invention relates to a power cylinder operated by fluid power and more especially a pneumatic cylinder.
Fluid power cylinders generally have an elongated cylinder housing in which a piston is arranged able to be moved by fluid actuation and which is connected with a piston rod extending at the front end of the cylinder housing.
In the case of the fluid power cylinder disclosed in the European patent publication 0 713 980 A2 control components are arranged in the cylinder housing and cooperate for the control of the fluid actuation of the piston. These control components comprise electronic control circuitry attached in an anchoring groove and valves accommodated in recesses in the cover of the cylinder housing.
One object of the present invention is to provide a fluid power cylinder of the type initially mentioned which despite its directly having control components for the actuation nevertheless possesses compact dimensions.
In order to attain this object a fluid power cylinder and more particularly a power pneumatic cylinder, is provided comprising:
a cylinder housing containing therein a piston receiving space in which a piston able to be moved by fluid actuation is arranged, which is kinematically coupled with a piston rod extending out at the front end of the cylinder housing,
a control system housing mounted on the rear end of the cylinder housing, which system housing contains control components cooperating for control of fluid actuation of the piston, such control components including an electrically actuated valve means and furthermore electronic valve circuitry and/or electronic control circuitry cooperating in the electrical control of the valve means,
electrical connection means provided externally on the control system housing for the supply of electrical control signals, which electrical connection means are connected in the control housing with the electronic valve circuitry and/or electronic control circuitry,
fluid connection means provided externally on the control system housing for the supply of an actuating fluid, which electrical connection means are connected with the valve means, whence control ducts emerge, which extend in the wall of the cylinder housing to the piston receiving space.
The fluid power cylinder of the invention may be designed with an extremely slim shape, since the relevant control components are placed in a rear extension of the cylinder housing. It is more especially possible to so select the configuration of the control system housing that its external form does not extend past the outline of the axially adjoining cylinder housing. It is furthermore relevant here that the valve means and the electronic valve circuitry and/or electronic control circuitry employed for its electrical control are accommodated safely in a further housing mounted to the rear on the cylinder housing, which further housing is termed the control system housing. It is thus possible to ensure that the relevant components are arranged close together at the same position, something which substantially facilitates manipulation of part during connection and/or servicing operations. The supply of the actuating fluid takes place by way of the fluid connection means provided on the control system housing, the supply of fluid to the piston receiving space taking place by way of fluid ducts termed control ducts integrated in the cylinder housing so that no loose fluid lines have to be installed on the periphery of the cylinder housing.
Further advantageous developments of the invention are defined in the dependent claims.
More particularly when the control system housing and the cylinder housing possess an at least generally identical outer form it is an advantage for a rectangular outline to be selected and more particularly one with a square shape. The fluid power cylinder may then be extremely simply installed and if necessary readily connected with other instrumentalities.
In the peripheral part of the piston receiving space it is convenient to provide sensor means, which serve for detecting the position of the piston and which are electrically contacted by means of suitable sensor signal lines or leads, arranged to extend into the control system housing. Here they may be connected with any electronic control circuitry present or connected with the electrical connecting means, by way of which an external control means may be connected.
The control system housing will more particularly possess at least one access opening, which is closed by a housing cover, which when required may be removed in order to permit access to the control components accommodated in the control system housing. The access opening is preferably provided laterally on the control system housing, it also being possible to have several access openings closed by housing covers, such openings being distributed about the periphery of the control system housing. In the case of a rectangularly shaped control system housing it is possible to provide a plurality of access openings on differently aligned side faces of the control system housing.
In the case of a particularly preferred form of the invention a housing cover is designed as a support for electronic valve circuitry and/or electronic control circuitry arranged on the inner side of the housing cover. Here in this case access may be had to the electronic valve circuitry and/or electronic control circuitry in an extremely simple and straightforward manner by doffing the housing cover.
If control system housing has a plurality of access openings distributed at the side around the periphery an arrangement is recommended in the case of which one access opening is opposite to the electrical drive means of the valve arrangement and a further access opening is arranged adjacent to the electronic valve circuitry and/or electronic control circuitry, the latter being more particularly so placed that the electronic circuitry is seated directly on the housing cover. This means that all control components significant for operation may be accessed if required in an extremely simple way.
The control components may comprise simple electronic control means, which for example includes a voltage conversion circuit or other components necessary or advantageous for the actuation of the electrical valve means. The electrical control signals necessary for operation may be supplied by way of electrical connection means, which are able to be connected by way of a cable with external electronic control circuitry. However, it is readily possible to provide electronic control circuitry in the control system housing instead of or in addition to valve control electrical circuitry in the control system housing, which electronic control circuitry preferably comprises a field bus electronic system and offers the possibility of linking the fluid power cylinder by way of a bus with other equipment or of connecting it to external control means. The electronic control circuitry may furthermore be provided itself with a control program, which causes a predetermined operational sequence to be implemented by the fluid power cylinder, when the electronic control circuitry is supplied by way of electrical connection means with external control signals.
In principle it would be feasible to design the control system housing as a body closed on all sides. It is however substantially more advantageous and also better from the point of view of saving space and materials to design the control system housing like a pot having a round or polygonal cross section and to attach it to the open side, which is opposite to the floor, to the fore on the rear side of the cylinder housing. It is in this manner that the cylinder housing will itself constitute the termination of the control system housing.
Furthermore there is the possibility of so accommodating the valve means in the inner space defined by the control system housing that even when the control system housing is mounted it extends between the floor of the pot-like control system housing and the cylinder housing and is secured here as well. It is however also possible to have an interlocking engagement between the above mentioned components, such engagement more particularly serving to produce the duct connections, by way of which the actuating fluid is supplied to the valve member and from which said fluid leaves the valve means.
In the case of a pneumatic fluid power cylinder it is to be recommended to provide all venting openings on the rear side facing away from the cylinder housing, of the control system housing. In this case each venting opening may be provided with a muffler and more particularly with an integrated spent air choke means to set the maximum piston speed.
In the case of the valve means in principle a wide variety of designs are possible, for example in the form of a five way valve or a four way valve. It is more particularly advantageous however to have a design with three way valves.